bf4a77ee0eac68d01f5ea5f44ba8144c English P12466 dataset Gareth Myers-McCann APEM Limited Data Operations Team dot@apemltd.co.uk pointOfContact 2024-03-14 MEDIN Discovery metadata standard 2.3.8 urn:ogc:def:crs:EPSG::32630 2023, APEM, POSEIDON, Northern Isles Seabird and Marine Mammal Surveys 2024-03-14 publication 2024-03-14 creation 2024-03-14 revision P12466_S01 This series includes the reporting and data deliverables for seasonal aerial surveys of seabirds and marine mammals east of Shetland in the Scottish Northern Isles. The surveys were completed as part of POSEIDON, a multi-year, multi-partner project funded through The Crown Estate OWEC programme and led by Natural England. The series constitutes: The first seasonal (September to October 2023) report outlining results from digital aerial surveys conducted in September 2023 within the Northern Isles under the POSEIDON project and commissioned by Natural England. Surveys were undertaken using APEM’s high-resolution camera system to capture digital still imagery of birds and marine megafauna within the Survey Area. The survey was successfully carried out across one day in September 2023. A total of 4,851 observations were recorded during the survey in September 2023, of which 4,769 were observations of birds and 82 were observations of marine megafauna Gareth Myers-McCann APEM Limited Data Operations Team dot@apemltd.co.uk originator The Crown Estate +44 020 7851 5000 1 St James's Market London SW1Y 4AH United Kingdom enquiries@thecrownestate.co.uk https://www.thecrownestate.co.uk/ custodian notPlanned Delimited Species distribution GEMET - INSPIRE themes, version 1.0 2008-01-06 revision Bird counts SeaDataNet P021 parameter discovery vocabulary 2009-11-16 revision Research Research and Development Activity Marine Environmental Data and Information Network Marine Environmental Data and Information Network otherRestrictions No restrictions to public access. Data is freely available for research or commercial use providing that the originators are acknowledged in any publications produced. eng biota Charting Progress 2 Sea Areas 2009-06-18 creation Northern North Sea Charting Progress 2 Sea Areas 2009-06-18 creation Scottish Continental Shelf ICES Rectangles 2009-05-01 creation 48E8 ICES Rectangles 2009-05-01 creation 50E8 ICES Rectangles 2009-05-01 creation 48E9 ICES Rectangles 2009-05-01 creation 50E9 ICES Rectangles 2009-05-01 creation 48F0 ICES Rectangles 2009-05-01 creation 49F0 ICES Rectangles 2009-05-01 creation 50F0 International Hydrographic Bureau, Limits of Oceans and Seas 1954-01-01 creation North Sea SeaDataNet vertical extent keywords 2010-01-01 revision troposphere -2.0000 1.0000 59.5000 61.0000 2023-09-27 2023-09-27 https://www.marinedataexchange.co.uk/details/TCE-3991/summary A link to the web service or dataset. https://www.marinedataexchange.co.uk A link to the general host site. dataset MEDIN data guideline for photo-identification of cetaceans and surface swimming sharks 2011-02-02 publication Cetaceans and surface swimming sharks may be detected in offshore aerial surveys true MEDIN data guideline for ad hoc sightings 2012-12-19 publication No specification of direct applicability to digital aerial surveys of birds true The survey was conducted using APEM’s bespoke camera system, termed “Shearwater V”, customised by in-house specialists for surveying the offshore environment. The camera system is integrated with custom flight planning software that allows each survey flight line to be accurately mapped before the aircraft leaves the ground. Each image capture node is precisely defined, allowing the system to fire the camera exposures at exactly the right location. This ensures that each survey is flown with the same orientation and the camera is triggered at the same position within set tolerances. APEM’s flight planning software enables tolerances along survey lines to be set, meaning the camera system would automatically abort data capture should the aircraft drift away from the planned flight line. The process of automatically aborting data capture is called a ‘cutout’. Should this occur, the plane is required to revisit and resurvey the affected section of the survey line. APEM’s on-board camera technician continually monitored the imagery as it was collected to ensure data collected was fit for purpose. The camera technician would make the decision to cease data collection should conditions become unsuitable for surveying or data collection. Subsequently, the survey would then be resumed at the next earliest opportunity. All completed surveys therefore maintained conditions conducive to successful surveying. Favourable conditions for surveying were defined as: a cloud base (lowest altitude of the visible portion of the cloud) of at least 1,300 ft, according to a geoidal model, to ensure there is no cloud below the planned altitude of the aircraft, visibility of greater than 5 km, wind speed of less than 30 knots, and sea state of 4 (moderate) or less. Naturally, the cloud base may vary in altitude, but aircraft will always fly lower than the lowest cloud level, if cloud base is lower than the planned aircraft altitude the survey would not take place. Whilst the image footprint and GSD both increase with altitude, the flight plan tolerances and focus of the camera lenses ensures no discernible differences occur within the range of altitudes potentially flown. Wind speed was recorded at the same altitude as the aircraft, whereas sea state was determined from the appearance of the sea surface recorded by the onboard aerial survey technician. The two measures therefore do not necessarily correlate. For safety reasons, no surveying can take place in icing conditions. Due to areas of high terrain, part of line 7 was planned at a higher geoidal altitude of 1,365 ft and lines 3 and 4 were split. Lines 3 and 4 are distinguishable in 4 separate sections: 3a, 3b, 4a, 4b. Lines in 3b and 4b refer to the area of the lines that overlap on their east-west axis. Data capture comprised digital still images of an average 1.5 cm GSD. Images from each of the three cameras are processed at each node, resulting in slight variation in GSD across the swath width. GSD is smaller than 1.5 cm GSD at the nadir and increases with distance from the nadir, resulting in an average GSD of 1.5 cm. Image resolution is therefore clearest at the nadir, although the variation is small. Images were collected in a continuous transect-based design along a single line covered by three overlapping cameras, using a Global Positioning System (GPS) linked, bespoke flight management system to ensure the tracks were flown with a high degree of accuracy. The aircraft’s internal GPS and Inertial Motion Unit (IMU) systems record to an accuracy of +/- 3 to 5 m as standard. The flights occurred on the 27th of September 2023, the aircraft surveyed lines 6 to 9 (take off at 06:46, landing at 11:06), stopping to refuel and continued with lines 1 to 5 and 7 (take off at 12:23, landing at 16:18), respectively. The camera system captured abutting imagery along nine survey flight lines spaced approximately 22 km apart within the Survey Area. The total Survey Area was 21,594 km2. The aircraft collected the data at an average altitude of approximately 1,460 ft (445 m) according to the ellipsoid model as recorded by GPS, equivalent to 1,300 ft (396 m) above geoidal mean sea level, and at a speed of approximately 120 knots. On line 4, the flight altitude was decreased to 1,150 ft to avoid low cloud on the line, resulting in a decrease in image footprint and GSD. At 1,300 ft, ~0.09 square kilometres (km2) is captured at 1.5 cm GSD at each image node. At 1,150 ft, ~0.08 km2 is captured at 1.36 GSD at each image node. As a consequence, image resolution is increased, with the target coverage still achieved. Images were collected continuously along the survey flight lines with slight overlap between image nodes. To avoid double-counting due to image overlap, all image footprints are merged into a single file, for which total area is calculated. A total of 7,832 nodes were initially captured. Of these, 7,579 were used for analysis. The difference reflects nodes removed during clipping to the boundary area. Total analysed coverage was calculated to be 3.42% generated from 7,579 image nodes. The target coverage of 3% was achieved including a redundancy of an additional 0.42%, which is over 10% contingency with respect to the target coverage. Effort data is calculated as the area (km2) per image footprint using trigonometric methods and the pinhole camera model (the mathematical relationship between the coordinates of a point in three-dimensional space, and its projection onto the image plane of an ideal pinhole camera). Effort is dependent on altitude, camera angle and aircraft position (pitch, roll and yaw), accounting for variation both between image nodes and individual cameras at each node. Effort data is only calculated for analysed images. It is therefore possible that some images have an effort value of zero. The effort values provided in the GPS log reflect the total footprint of each image and do not account for overlap. Therefore, summing these values for a survey would result in an overestimate of effort. The true effort for a given survey is calculated geospatially by creating polygons for each image footprint and removing the overlapping areas. Summing the analysed footprints and comparing against entire survey area gives the percentage analysed. Imagery was captured in raw format and post-processed to ensure optimal quality for the subsequent stage of image analysis, to extract information on marine fauna or other notable occurrences. When a survey was completed, data were checked to ensure the number of lines and the number of images collected was correct, and that the quality of the imagery was acceptable. Once image analysis was completed, further quality assurance (QA) processes took place. Weather conditions during the survey were conducive to collecting and analysing imagery for the purposes of providing data on the identification, distribution, and abundance of bird species and marine fauna within the Survey Area. Measures were taken to minimise glint and glare, such as avoiding surveying when the sun angle had the greatest potential to impact image quality. Furthermore, data collected provided coverage of 3.42%, thus exceeding the 3% coverage required, enabling sufficient coverage to be collected should images be affected by glint or glare.